1. Field of the Invention
The invention relates to a method and system, including an operating system, for administering a plurality of storage devices, on a network, such as a storage area network which includes controllers. More specifically, the invention relates to a method and system for assigning identification signatures, described herein as Lun signatures, to different types of storage devices on the network to create a uniform signature methodology within an operating system on a host controlling the network. As a result, different classes of storage devices can be administered by the host on the same network.
2. Description of the Prior Art
In networks, in particular, networks including plural storage devices or storage arrays distributed throughout the network, the storage devices typically are identified by unique signatures which are used to identify and configure the devices on a host such as a server. Depending upon the type of device, the signature provides a specific identification unique to that storage device, which is used by the host system controlling the network to enable different functionality, depending on the device, including the aforementioned identifying, configuring and administering of the specific device. For purposes of this disclosure, such signatures will generally be referred to as a logical unit number (Lun) signatures.
It is noted that conventionally, the term xe2x80x9cLun signaturexe2x80x9d has been used by EMC Corporation and others with reference to different types of storage arrays commercially available from EMC Corporation. While the term Lun signature is used herein for ease of reference and understanding in describing the system and method, it is noted that such term is not limited to the specific types of signatures used by EMC Corporation, and is intended to encompass any such type identification, providing similar functionality, as used in the industry to provide identification and allow configuring and administration of storage devices in a network, as will be readily apparent to those of ordinary skill in the art.
In the past, as technology has developed, different types of storage devices have used different protocols in assigning an identification signature for use in identifying, configuring and controlling such devices on a network. In a specific example, as already noted, such signatures have been employed in connection with storage arrays such as those originally commercially available under the name Clariion, from Data General Corporation, now EMC Corporation. The Clariion-type systems started employing the signature for a derived path identification on the network, and was known as a Lun signature. The Lun signature was specific to the storage processor identification for each storage array on the network. In this context, it will also be appreciated that by the term Lun signature as used herein, is meant the path identification, i.e., ID for a given adapter on a host system, to a specific storage array on a network.
Such signatures can be employed in systems employing a host, such as a server, administering a plurality of storage arrays on a fibre channel-type system, with the host communicating with the various storage arrays through a switch, or where all devices are physically connected without a switch in a loop, as well as on SCSI protocol based systems.
So long as a single type of storage array having a uniform Lun signature protocol is used on a network, it is easy to configure and operate the network. However, as different types of storage arrays use different types of Lun signatures, a performance problem arises, which also compromises data integrity as a result of supporting older styles of Lun signatures.
More specifically, one example of prior art methods of tracking Lun signatures within an operating system such as DG/UX, originally available from Data General and now from EMC Corporation, involves tracking Lun signatures solely with disk-based signatures, except for the aforementioned Clariion-type storage arrays. Storage arrays such as those available under the name Clariion, and other equivalent type arrays, are tracked using a unique vendor specific SCSI mode page which provides the vendor specific signatures of the storage processors (SPs) controlling the storage array.
As new technologies have been developed in fibre channel storage area networks, storage array network (SAN) and network attached storage (NAS) environments, it has become more difficult to accommodate tracking the prior art arrays which used disk-based signatures. More specifically, current technologies operate primarily on world wide name (WWN) based signatures, which are incompatible with the older signatures.
More specifically, prior to the introduction of SAN, every Lun signature on a disk-based signature type device was unique to the specific device. Therefore, if a Lun 0 was found for storage processors having IDs 1 and 2, for example, then there could not be another Lun 0 with the same storage processor (SP) ID. However, with SAN technology, there can be multiple Lun 0s in the same array configured, so a different method other than SP IDs is needed.
In other types of arrays such as those available from EMC Corporation under the name Symmetrix, they do not have SP IDs and only support the WWN standard. Thus, in the case where disk-based signatures are used, this results in both slow and potentially dangerous operations if disk-to-disk copying is done.
Thus, in accordance with the method and system described herein, the prior art problems of administering networks with differing types of storage devices and/or arrays, is avoided, along with other advantages provided by the system and method disclosed herein.
In one aspect, the invention is directed to a method of configuring an operating system on a host. The host is connected on a network for administering a plurality of storage devices. The network has controllers thereon. The method involves, for storage devices which are storage arrays, and are on the network, and which support world wide name signatures, building a first class of unique Lun signature for each such storage device, which is based on the world wide name signature of each storage device. The Lun signature is built in the operating system, and in the controllers on the network.
For storage devices, which are storage arrays, and are on the network but which do not support world wide name signatures, but have storage processor based signatures, a second class of unique Lun signature is built for each such storage device based on the storage processor based signature of each such storage device, in the operating system and in controllers on the network.
For storage devices which are not storage arrays, and are on the network, a third class of unique Lun signature is built for each such storage device, in the operating system and in controllers on the network.
In a more specific aspect, each Lun signature has a predetermined structure which identifies the type of storage device associated therewith. If a specific storage device does not include a Lun 0, there is created a unique fake Lun 0 for the device, in the operating system and in controllers on the network. The Lun 0s in the operating system are used to support communications with storage devices on the network to allow the operating system to size the network. More specifically, a Lun signature is allocated for every path on the network.
In another aspect, there is described a host system, for example, a server, capable of administering a plurality of devices on the aforementioned type of network. The host system includes at least one processor, although it can be a NUMA class type host system with multiple processors. The host system includes programs configured for administering the network, and the programs include an operating system having a file system with a virtual device manager capable of assigning Lun signatures within the operating system to represent storage devices on the network based on the storage device class. The file system is capable of assigning Lun signatures within the operating system to: (1) storage devices, which are storage arrays which support world wide name signatures, by building a first class of unique Lun signature for each such storage array connected on the network, based on the world wide name signature of each storage device in the operating system, and in the controllers on the network; (2) for storage devices, which are storage arrays, on the network which do not support world wide name signatures, but have storage processors based signatures, by building a second class of unique Lun signature for such storage device, based on the storage processor based signature of each such storage device, in the operating system and on controllers on the network; and (3) for storage devices, which are not storage arrays, on the network, by building a third class of unique Lun signature for each such storage device, in the operating system and in controllers on the network.
In yet still another aspect, there is disclosed an operating system for use on a host system capable of administering a plurality of storage devices when connected thereto on a storage area network, with controllers on the network. The operating system includes a file system as previously described with reference to the host system.